Conventional solvents have fixed physical properties which can lead to significant limitations in their use as media for reactions and separations. Many chemical production processes involve multiple reactions and separation steps, and often the type of solvent that is optimum for any one step is different from that which is optimum for the next step. Thus it is common for the solvent to be removed after each step and a new solvent added in preparation for the next step. This removal and replacement greatly adds to the economic cost and environmental impact of the overall process. Therefore, there exists a need for a solvent that can change its physical properties.
Solvents are commonly used to dissolve material in manufacturing, cleaning, dyeing, extracting, and other processes. In order for a solvent to dissolve a material quickly, selectively, and in sufficient quantity, it is usually necessary for the solvent to have particular physical properties. Examples of such properties include hydrophobicity, hydrophilicity, dielectric constant, polarizability, acidity, basicity, viscosity, volatility, hydrogen-bond donating ability, hydrogen-bond accepting ability, and polarity. At some point in such a process after the dissolution, separation of the material from the solvent may be desired. Such a separation can be expensive to achieve, especially if the solvent is removed by distillation, which requires the use of a volatile solvent, which can lead to significant vapor emission losses and resulting environmental damage e.g., through smog formation. Furthermore, distillation requires a large input of energy. It would therefore be desirable to find a non-distillative route for the removal of solvents from products. This is particularly difficult if the solvent and the product are both very low in polarity.
US Patent Application Publication No. 2008/0058549 discloses a solvent that reversibly converts from a nonionic liquid mixture to an ionic liquid upon contact with a selected trigger, such as CO2. The nonionic liquid mixture includes an amidine or guanidine or both, and water, alcohol or a combination thereof. However, that document does not provide certain advantages of the present invention as described below.